Although most bacterial infections are successfully diagnosed by culture, serologic testing is performed for antibodies to screen for past, recent, or existing infection in those with negative cultures. Clients in whom these tests are performed usually have sustained a fever of unknown origin or have been treated with antimicrobials. Table 3-10 indicates the commonly performed tests for recent bacterial infections for identification and titers that are suggestive of recent infection. Also, specific individual serologic tests that have special applications in bacterial antibody detection of recent or existing infectious diseases are individually outlined and discussed. They include staphylococcal, streptococcal, and febrile/cold agglutinin tests.